The steerability of Bob by Alice (\(A\rightarrow B\) ) for a two-mode Gaussian
state with Gaussian measurement can be quantified by [1]}
\(\mathcal {G}^{A\rightarrow B}(\sigma _{AB})=\max \bigg \lbrace 0,\frac{1}{2}\ln \frac{\det \mathbf {A}}{\det \sigma _{AB}}\bigg \rbrace . \) 
